Lee is this story in Spanish here.
The near-Earth object was likely ejected into space after an impact thousands of years ago. This could now bring new knowledge to the science of asteroids and the Moon.
The small near-Earth object 2024 PT5 captured the world’s attention last year after a NASA-funded telescope discovered that it stayed near our planet, but never orbited, for several months. The asteroid, which is about 10 meters wide, poses no danger to Earth, but its orbit around the Sun closely matches that of our planet, suggesting it could have come from nearby.
As described in a study published On January 14, in Astrophysical Journal Letters, researchers collected further evidence for the local origin of 2024 PT5: it appears to be composed of rocks broken off the surface of the Moon and ejected into space after a large impact.
“We had the general idea that this asteroid might have come from the Moon, but the smoking gun came when we discovered that it was rich in silicate minerals – not the ones you see on asteroids but the ones that were found in lunar rock,” said Teddy Kareta, an astronomer at the Lowell Observatory in Arizona, who led the research. “It looks like it hasn’t been in space for very long. perhaps only a few thousand years, for there is a lack of spatial alteration which would have made its specter blush.”
The asteroid was detected for the first time on August 7, 2024, by the NASA-funded Sutherland Telescope in South Africa of the University of Hawaii’s Asteroid Land Impact Last Warning System (ATLAS). Kareta’s team then used observations from the Lowell Discovery Telescope and NASA’s infrared telescope (IRTF) at the Mauna Kea Observatory in Hawaii to show that the spectrum of sunlight reflected from the surface of the small object did not match that of any known type of asteroid; instead, the reflected light more closely matched the Moon’s rock.
A second clue came from observing how the object moved. With asteroids, debris from the space age, like old rockets historic launchescan also be found in Earth-like orbits.
The difference between their orbits has to do with how each type responds to the pressure of solar radiation, which comes from the momentum of photons – quantum particles of light from the Sun – which exert a tiny force when they hit a solid object in space. This exchange of momentum between many photons over time can push an object ever so slightly, speeding it up or slowing it down. While a man-made object, like a hollow rocket booster, will move like an empty tin can in the wind, a natural object, like an asteroid, will be much less affected.
To rule out 2024 PT5 as space junk, scientists from NASA’s Center for Near Earth Object Studies (CNEOS), managed by the agency’s Jet Propulsion Laboratory in Southern California, analyzed its movement. Their precise calculations of the object’s motion under the force of gravity ultimately allowed them to look for additional motion caused by the pressure of solar radiation. In this case, the effects proved too small for the object to be artificial, proving that 2024 PT5 is most likely of natural origin.
“Space debris and space rocks move slightly differently through space,” said Oscar Fuentes-Muñoz, study co-author and NASA postdoctoral researcher at JPL working with the CNEOS team. “Man-made debris is generally relatively light and is repelled by the pressure of sunlight. The fact that PT5 2024 does not move in this way indicates that it is much denser than space debris.
The discovery of 2024 PT5 doubles the number of known asteroids thought to come from the Moon. Asteroid 469219 Kamo’oalewa was found in 2016 with an Earth-like orbit around the Sun, indicating that it may also have been ejected from the lunar surface after a large impact. As telescopes become more sensitive to smaller asteroids, more potential rocks on the Moon will be discovered, creating an exciting opportunity not only for scientists studying a rare population of asteroids, but also for scientists studying the Moon .
If a lunar asteroid can be directly linked to a specific impact crater on the Moon, studying it could provide insight into cratering processes on the pockmarked lunar surface. Additionally, material from deep within the lunar surface – in the form of asteroids passing close to Earth – could be accessible to future scientists for study.
“This is a story about the Moon told by asteroid scientists,” Kareta said. “It’s a rare situation where we went to study an asteroid but then strayed into new territory in terms of the questions we can ask at PT5 2024.”
The ATLAS, IRTF, and CNEOS projects are funded by NASA’s Planetary Defense Program, managed by the Planetary Defense Coordination Office at NASA Headquarters in Washington.
For more information on asteroids and comets, visit:
https://www.jpl.nasa.gov/topics/asteroids/
Ian J. O’Neill
Jet Propulsion Laboratory, Pasadena, California.
818-354-2649
ian.j.oneill@jpl.nasa.gov
Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov
Kevin Schindler
Lowell Observatory Public Information Officer
928-607-1387
kevin@lowell.edu
2025-007